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Question: Visible glass cylinder tightening
#751488 Fri Jul 10 2020 06:14 PM
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smokey1 Offline OP
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Originally gas pump glass cylinders were glued/bonded into place using a white lead based paste mixture providing a strong leak proof bond between cast iron pump castings and glass itself while supporting steel rods surrounding the assembly providing an even clamping pressure on assembly.

With vintage concrete mix removed & glass cylinder cleaned(w/solid crack-free top/bottom edge) using new cork gaskets between glass/castings or glass-gasket-steel band-gasket-pump casting, how much tightening on supporting steel or brass rod nuts should be applied once final assembly takes place? Tightening in a criss-cross pattern for even pressure.

Before someone says, 'tight enough to compress the new cork gaskets, but loose enough that the glass does not shatter', would be great to hear from restoration members who have practical experience and can share knowledge on the subject after fitting and final tightening these vintage glass cylinders.

Realize there might not be an inch-pound torque wrench specification, but again some practical experience would be very welcome.

Looking to do final assembly and ideally like glass to remain in place when the gas pump is someday transported on its side without disassembling the glass back out of the gas pump if possible.

Thank you in advance

Last edited by smokey1; Fri Jul 10 2020 06:25 PM. Reason: word
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Re: Question: Visible glass cylinder tightening
smokey1 #751491 Fri Jul 10 2020 06:50 PM
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Tightening these is always scary for me. I usually tighten them lightly - and I know thats not a definitive term - and then let it sit and come back to it and hit it a little more. Typically, I still have other work to do on the pump at this point so doing it slowly over a few days is not a big deal.

I'm usually shipping these, so I'm using lock washers too. I usually have the pump on a skid by this point too. Nice to lay the pump back down once I feel its tightened well, and then back up, see if anything shifted or changed under the movement. Then tighten straight up again if needed. I dont like tightening if its not sitting up, seems like a bad idea. Keep repeating up and down placement of the pump until nothing is changing or moving on me.

The vibration in shipping is so horrible on nuts and bolts, vibrating them loose AND the pumps are usually laying down for shipment, which sucks even more. If I wasnt shipping be a whole less worried about getting it right.

Last edited by Paul Bell; Fri Jul 10 2020 06:51 PM.
Re: Question: Visible glass cylinder tightening
smokey1 #751492 Fri Jul 10 2020 07:08 PM
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smokey1 Offline OP
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Paul,
This is exactly the great info I was looking for. Thank you Sir.
I like the idea of tightening and tighten again. Sneaking up on the vertical clamping pressure makes since.

Just had a thought, wish I owned a dial indicator and had use for one outside this exercise.
Wonder if this would work?
Dial indicator needle touching/positioned on top bell casting.
Tightening down rod nuts until the compression basically stalls the dial needle movement, then a little extra stretch on threads after a day or two of glass resting.

Re: Question: Visible glass cylinder tightening
smokey1 #751496 Sat Jul 11 2020 12:19 AM
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I dont think it tightens down in pure "up/down" if that makes sense, some lateral and angling going on when tightening. The dial indicator would be interesting but not really tell you the whole story I guess.

Glad to be of help! Keep in mind that the glass is pretty good in compression IMO, should be OK, it's actually more dangerous when you are taking the glass off.

Re: Question: Visible glass cylinder tightening
smokey1 #751498 Sat Jul 11 2020 05:33 AM
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AIways... tighten with pump in standing position. In our tightening routine, I use the old cylinder head auto technique......cross tightening. Install lock washers and finger tighten all the nuts. Using a box end wrench, hold it very near the end around which the nut to be tightened....this keeps you from applying too much force. Reduces natural torque from the wrench. Now start on opposite rods. Tighten snug watching the lock washer compress.....lightly. Move to the next set 90 degrees from where you started. repeat the process. then move 45 degrees and again. Once you have made the initial rotation, go back and do it again...always watching the lock nut compression and feeling the nuts through the wrench. You might be intimidated but glass is very strong in the compression stage....which is what you have here. When you are satisfied, let it set for a day. Check back and adjust the system where needed. One thing that I should mention is that once I set the cylinder, on the new cork in the base, I caulk it in place. It keeps it safe and helps eliminate dirt from getting into the area around the glass. All done before I install the rods and tighten. Makes for an easy clean up of the finished seal without the rods being in the way. I've used this system for over 30 years. Hope it works for you? Regards, Paul www.severngaspumps.com

Re: Question: Visible glass cylinder tightening
smokey1 #751509 Sat Jul 11 2020 08:54 AM
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smokey1 Offline OP
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Another great tip regarding watching compression of lock washers and holding box end wrench close to fastener to reduce leverage as each one is evenly tightened.
100% on the cross tightening technique. I just ordered some washers. While waiting on those to come in going to thread new brass rods after measuring for each over all length this weekend.

Re: Question: Visible glass cylinder tightening
smokey1 #751521 Sat Jul 11 2020 01:22 PM
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Yeah, I do the star pattern cross tightening too...


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